Pump



Oct. 12, 1937.- F, Dmns, JR 2,095,316

PUMP

s sheets-sheet 1 Original Filed Dec. 14, 1934 ATTORNEYS Oct. 12, 1937. F. DAvls, JR

PUMP

Original Filed Dec. 14, 1934 3 Sheets-Shel#l 2 A Ri INVENTOR BYS ,v im

ATTORNEYS Oct. 12, 1937.

F. L. DAVIS, JR

PUMP

Original Filed Dec. 14, 1934 3 Sheets-Sheet I5 INVENTOR EranL WiL/:

BY l I s ATTORNEYS Patented Oct. 12, 193.7

UNITED STATES PATENT OFFICE PUMP Frank L. Davis, Jr., Kenilworth, N. J., assignor to The Watson-Stillman Co., Roselle, N. J., a corporation of New Jersey 8 Claims. (Cl. 1 .03-1'13) I'I'his invention relates to multi-cylinder, continuous delivery pumps and more particularly to hydraulic pumps of a type wherein the pump plungers are operated by a swash plate to deliver uid at high pressure for operation of a press or other mechanism.

Important objects ofthe invention are, to provide such a pump of generally improved'design; to provide for easy accessibility of the working parts of the pump mechanism and facilitate 'adjustment, repair and replacementV of the parts; to provide an improved driving mechanism "for the pump plungers; to provide an improved em- `bodiment-of the pump cylinder, plungers and l5 valves in a unit, and to provide an improved organizationof the driving mechanism and pump unit enabling the latter to be readily detached from the driving mechanism and readily replaced and also enabling pump units-of different capacity to be connected interchangeably to the driving mechanism. Y f

Other objects of theinvention will appefr hereinafter. Y

In the drawings, Fig. 1 is a vertical longitudinal sectional view of the pump apparatus;

Fig. 2 a transverse section on the line 27--2 cfu Fig. 1; l

Fig.1;" l .Y v Y Fig. 4 a sectional side view of a portion of the power transmission mechanism, showing it adjusted to neutral or non-stroke position; and

Fig. 5 a faceview of the pump unit. The pump apparatus includes -a--multi-cylinder pump unit embodying all the parts of the pump proper, and a cooperating power .transmission unit operatively connected to the pump .unit and embodying all ofthe mechanism required for transmission of power to the pump plungerfs'ito operate them in a Idesired manner'. These units are detachably connected, with the mechanisms in a spaced relation, for reasons which will appear hereinafter.

The power transmission unit will be ilrst described. It includes a fluid-tight casing I form ing a housing for the working parts ofthe transy mission mechanism and adapted to contain a bath of oil atV itsbottom-tolubricate the mechanism. The mechanism is ofv the swash plate type.

`5,0 It includes a drive shaft 2 extending horizon- 1 tally entirely through the interior of the casing and projecting outward through apertures in the opposite end walls of theA casing. Formed on or xedto said walls are annular members I and 55 4 encircling the shaft, and tted within 'saidr Fig. 3 a transverse section onthe line 3 3 of annular members are ball bearing assemblies i and 6 rotatably supporting the shaft. Screwed into the annular member 3 outward of the ball bearing` assembly 5 there is a closure disk 1. The shaft projects outward through an aperture in 5 the disk and the'latter is provided with a sealing packing 8 fitting the. shaft. The bearing 5 is designed to resist outward axial thrust on the shaft. The annular member 4 is cup-like and apertured to receive a reduced extremity of the l0 shaft end provided witha sealing packing 9 :dtting the shaft. The portion of the shaft within the casing is enlarged and has shoulders abutting the inner raceways of the ball bearing assemblies `to hold the shaft against endwise shift. Outside 15 of the casing an electric motor or other source Aof power, not shown, will be connected to the shaft.

Within the casing I there is a tubular swash member S encircling the shaft. The shaft has a 20 squared vportion I0 to which the swash member lis heldto rotate with the shaft and also to tilt ,relatively to the shaft axis. VFor tiltably mounting tle swash member on the shaft the latter has a pair of trun'nion pins I I projecting diametrical- 25 ly from opposite sides Iof the squared portion of the shaft. t Said pins have frusta-conical portions V"tted within'y correspondingly shaped aligning bores in the shaft, and cylindrical portions protrudlng from the shaft. Interposed between said 30 protruding ends and the swash member there are roller bearing assemblies I2 including inner race members tted on the ends of the pin's and outer race members fitted within the swash member. A bolt I3 extending through aligning axial Abores 35 in the trunnlon pins holds the frusto-conical portions of the pins seated in the shaft bores.

An annular member I4 enci'rcles the swashmember. This member I4 is connected tothe swash member te tut' therewith en the shaft, but 4o f 1e held against rotation with the swash member and shaft. The swash member is operatively connected Ato the member I4 to impart thereto a universal tilting or swash rocking movement so that the member-I4 may be'termed a follower member. The. connections for 'operating the pump plungers are made through the follower member. For suitable mounting of the latter the swashmember is made rather long. It surrounds the squared portion of the drive shaft and also an` adjacent cylindrical portion of the shaft and has a portion with a cylindrical periphery I5. .t f .Y

- The annular follower member I 4 has a disk-like head portion I4* surrounding the trunnioned 55 portion of the swash member, and a tubular shank portion I4h with a cylindrical interior surface I6 concentric with the peripheral surface I5 of the swash member. Between said surfaces there is a pair of roller-bearing assemblies adaptied to resist both radial and axial thrust. They include frusto-ccnical rollers I1, outer race members I8 fitting the inner surface I6 of the follower member, and inner race members I9 fitting the periphery I5 of the swash member. 'Ihe rollers of the two bearings are disposed with their axes inclined inward toward each other, for resistance of axial thrust in both directions. A ring 20 disposed between the outer race members of the bearings holds the bearings in a spaced relation, and the inner race member of the bearing nearest the trunnion mounting of the swash member abuts a shoulder 2I on said member. A threaded ring or nut 22 screwed on the remote end of the swash member abuts the inner race member of the adjacent bearing and removably holds both bearings in place. The bearings hold the follower member in a definite relation to the swash member and the two members maybe tiltably adjusted as a unit to vary their obliquity to the axis of the drive shaft.

There is provided a mounting to support the follower member for universal tilting by the swash member andhold it against rotation with the swash member about the axis of the drive shaft. Said mounting includes a supporting ring 23 encircling the head I4a of the follower member. AAt diametrically opp'site ints the supporting ring bears trunnion pins 2 disposed on a horizontal axis intersecting the axisl of the drive shaft 2 at right angles. Said pins are fixed to the ring and project therefrom into bearing blocks- 25. The

latter are supported by brackets 26 borne by the adjacent end wall of the casing I. The ring 23 also bears two fixed trunnion pins21 projecting inward at diametrical points and on 'an axis at right angles to the axis of the pins 24. The axes of the pins 24 and 21 lie in a plane including the trunnion axis of the swash member. Pins 21 have a swivel fit in bearing blocks 28 and the latter are removably tted in recesses 29 formed in bosses on the periphery of the follower head rI4. Said recesses open through the outer face of the follower head for insertion and removal of said bearing blocks.

The brackets 26 borne by the casing have guide forks in which the bearing blocks 25 for the supporting ring trunnions are slidably fitted to shift longitudinally of the drive shaft axis. Back of said forks there are mounted plungers 30 to engage the bearing blocks in the forks. Springs 3| urge said plungers'against the blocks. Thereby, through the blocks 25 and the trunnions 24 the ring. 23 is-pressed rearwaifdtto hold the bear-- ing blocks 28 back in the recesses 29 and yieldably maintain .the supporting ring in a definite relation to the follower member I4;

The casing end wall bearing the brackets 26 and facing the follower member and itssupportvprising links 41.

nections between the follower member I4 and the pump plungers.

Said operative connections include crossheads 33 each having a cylindrical periphery slidably fitting in one of the guides 32. Connecting-rods 34 operatively connect the follower member to the crossheads. For universal connection said rods have spherical ends. To connect one end of the vrods to the follower member the latter is formed with a circular series of sockets 35 whose number and spacing corresponds to that of the crosshead guides. In each socket there is a sectional bearing for an end of one of the connecting rods, including a bearing block 36 with a concave seat for the rear of the spherical end of the rod, and an annular bearing member 31 with a concave seat for the front of said end. The member 31 has a screw-threaded connection with the follower member permitting disconnection of the rod. These bearing structures provide push-andpull connections between the follow'er member and the connecting rods. Each crosshead 33 has a socket 38 with a concave bearing seat at its bottom for the opposite end of a connecting rod. A bearing bushing 39, with a concave bearing surface for the rod end, is in screw-threaded connection with the crosshead to detachably hold the connecting rod and provide apush-and-pull connection between the rod and the crosshead. Each crosshead is operatively connected to' a plunger of the pump located outside of the casing. a The stroke of the crossheads-and the connected lungers is dependent upon the tilt of the swash member S and the follower member I4 upon the drive shaft 2. When said members are disposed in their position of maximum obliquity, a's-shown in Fig. 1, the maximum stroke will be obtained. When they are disposed, as shown in Fig; 4, with the follower head I4a and the supporting ring 23 in a plane normal to the axis of the drive shaft, stroke will be eliminated and the crossheads and pump plungers will remain in neutral positions as the drive shaft and the swash plate S are ro- Means are provided/ to adjust the obliquity of the swash member and follower according to the stroke required. Upon the drive shaft there is mounted a tubular slide 40 keyed, as at 4I, to rotate with the shaft, and slidable end-wise thereon. At one side of the drive shaft the slide bears a transverse pintle 42, and at the opposite side of the shaft the swash memberl S bears fa pintle 43 parallel to said first pintle and mounted in an extension 44 on the rear end of the swash member. Said extension also bears an adjustable stop screw 45 to contact the drive shaft and limit the no-stroke adjustment of the swash member. Between the Aslide and the swash member there is an operative connection com- The 'latter straddle the Ashaft and have their opposite ends pivoted on .the pintles 42 and 43. Shift of the slide to the left, with reference to Fig. l, exerts a. pull upon said links to tiltthe swash member and follower toward neutral or no-stroke position. Shift toward the right exerts a thrust upon the links and increases the obliquity of the swash member and thereby increases the stroke. 'I'he links are so disposed as to produce a toggle actio'n in which the mechanical advantage or leverage increases as the slide is shifted toward the right. Contact of the interior of the adjacent end portion of the swash member with the drive shaft limits the pump cylinders.

, a,o95,s1e

tilt of the swashI member. Other suitable stop walls ofthe casing support the rock shaft and,-

outside of thecasing an operating arm or lever 58 is xed thereto. The shaft is also supported by an intermediate bearing 5| on a bracket 52 borne by the adjacentr wall of the casing. Amxed to the shaft at opposite ends of the latter bearing are depending radial arms 53 with forks 54 at their lower ends. 40 and bears diametrically projecting pins 56.

VThe latter have lbearings in blocks51 slidably iltting in the forks 54. The slide y'41| is externally threaded at one end and a nut 58 is screwed thereon to abut one counterbored face of the ring 55. An opposite, counterbored face of the ring abuts a race member of. a ball bearing assembly 58 disposed between said face and a shoulder 68 on the slide.

Thereby, the ring is held to the slide against axial shift. The ball bearing reduces friction between the ring and slide as the latter is shifted to the right by the thrust of the ring, as the operating arms 53 are rocked. To hold the ring against rotation with th slide it is provided with an upwardly extending radial arm 6| whoseupper end is slidably The latter is borne by the bracket 52 and extends parallel to the drive shaft 2. 4

To aiord access to the mechanism within the casing the# latter is provided with apertures la,

of liberal size, at the top and sides. Plates |b are detachably secured to the casing to close said apertures.

The pump unit occupies 'a position' outside of the casing and spaced from the casing wall bearing the cross-head guides 32. Said unit includes a pump bodyl 63 formed in the present instance of a single, integral metal block. Said block has a flat, substantially rectangular vertical face v64 (which may be termed the rear face) dat, horizontal topand. bottom faces 65 and 66 respectively, and flat, vertical side faces 81. 'The front face of thegblock is of a stepped form,'for a purpose which will appear-hereinafter. At itsv rear face the block has a circular series of bores 68 to form the pumpcylinders. Their number corresponds to the number of crosshead guides, and their axes are similarly spaced around a circle of the same diameter as that including the axes of the cylindrical crosshead guides. The boresare all parallel and horizontal and terminate short of the front face of the block. For a portion of their length adjacent the frontface they are of reduced diameter tol provide' a shoulder 69. A bushing 10, tted in the larger portion of each bore, bottoms against said shoulder: These bushings form the actual They -are in the present in'- stance much shorter than the bores. For a .length adjacent the rear face of the block the bores are screw threaded.

Forward of the series of bores 68 the block 63- has a pairv of bores 1| and 12 forming the intake and discharge eonduitsvrespectively of the pump unit. These bores are parallel and they extend crosswise horizontally from one side face 61 to A ring 55 encircles the slide cylinder-forming bushings 1|).

vides a flat horizontal surface 13, at one level. overlying the conduit 1|, and a similar surface 14, at a higher level, overlying the conduit 12. `In the present instance there are nine of the pump cylinder bores and eac'h is in fluid communication'with both conduits 1| and 12. To form said communication the block 63 has lnine parallel horizontal hores 15 arranged in a straight row extending crosswise of the front face of the lock. They extend straight rearward from then front face at a level midway between the conduits 1| a'nd 12. At the front face they are plugged.

Each cylinder bore |58V communicates with' one of the bores 15 through an4 individual bore; 16 formedV inthe block. In` the. present ,instance five of the bores` 16 extend straight downward from the top surface 65 of ithe block, two extend straight upward from theunder surface 66 and two extend obliquely from the side `faces 6110i -t-he block. At the outer surfaces of the block all of said `bores 16 are plugged. From the surface 14 of the block a row of vertical bores 11 extend` downward, across the discharge conduit 12and thence to the horizontal bores l15. Similarly, a

A row of vertical bores 18 lead downward from the surface 14- of the block. I'he plug may also have a `depending guid for a stem on the poppet valve therebeneath. The` valve. may be readily withdrawn upward through the bore 11 upon removal of the plug. A bushing 8| is fitted in each bore 18 between .the bore 15 and the inlet conduit 1|, and has abeveled seat for an upwardly opening check or poppet valve'82. The valves 82 control communication between thepump cylinders and the inlet conduit 1|. Each bore/'181s threaded along its upper end portion, and-a plug. 83 is screwed into it and has a head protruding from the surface 13 of the block. The. valves 82 may be readily withdrawn upward through the boi-ess 18 uponr removal of the plugs 83. Removal of the plugs -8| and 83 also renders the valves 88 and 82 accessible for grinding them in place. The

. conduits 1| and 12 are screw-threaded at their ,isconnected to one end of the conduit 12A in the block," and the opposite end of the conduit 'is closed by a threaded plug l81.

Plunger rods 88 are tted to reciprocate in the. pump cylinders 1|) and extend outward through the open rear ends of the bores 68. Headed, screw-threadedrbushings or glands 88 tting the plungers are'screwed into said ends of the bores 68 and bear against suitable-packing 98 surrounding the plungers, between said bushings and the Each crosshead 33 is "operatively and detachably connected to oneqfpthe pump plungers. The crosshead has `a screw-threaded axial socket 37| in its outer end,

and the plunger has a screw-threaded end Y82 an enlarged portion 83 abutting the end of the 35 it, and provided with a. head protruding from the said units.

crosshead and formed wrench.

The pump unit is detachably supported in operative relation to the power transmission unit by tie rods 94. In the present instance there are four of said rods in rectangular arrangement and extending 4in parallel relation through both of 'Ihey pass through apertured bosses 95 on the opposite end walls of the casing I and though bores 9B in the pump block 63. Between the pump block and casing I the tie rods have enlarged spacing portions 94a affording end shoulders to abut the rearface of the pump block and the adjacent bosses 95`and support the pump unit in a definite spaced relation to the transmissionunit. 'Ihe opposite ends of the tie rods are threaded, and nuts 91 are screwed thereon to abut the front face of the pump block andthe bosses 95 on the far end of the casing I and anchor the units in said relation. The tie rods support the pump and resist the pressure exertedvupon the pump block by the pumping action. At its end adjacent the pump unit the casing I has a troughlike extension 98 to catch leakage from `the pump cylinders. Said extension has an end Wall 99 engaging the under side of the pump block and affording additional support for the latter.

In the operation of the pump apparatus, assuming that the swash member is adjusted in a tilted relation to the drive shaft 2, the rotation of the shaft will cause a swash rotation of said member and the follower member I4 will receive a universal swash rocking movement from the for engagement by amember S. Said rocking movement is transmitted to the follower member from the swash member through the inclined roller bearings between said members. Since the follower member is held by its universal mounting against rotation with Ithe swash member the latter by cam action rocks the follower member to reciprocate the connected crossheads 33and pump plungers 88 in a manner to obtain continuous discharge through the .pump conduit 12. Referring to Fig'. 1, the plunger at the top is Withdrawn by the follower member I4 to the limit of its suction stroke, while the plunger at the bottom is pressed forward to thev limit of its compression stroke.v The plungers in between are in intermediate stroke positions. Rotation of the swash member and universal rockingof the follower member thereby will advance this relation of diametricazlly disposed plungers around the drive shaft axis so that the plungers will all be operated simultaneously but out of phase for constant delivery.

Upon the suction stroke of a plunger, fluid in the conduit 1I forces open one of the poppet valves 82 and flows to the pump cylinder through the connected bores 15 and 16, the suction holding the popp'et valve 80 closed. Upon the pressure stroke of theplunger the uid is forced out of the pump cylinder, through the bores 16 and 15, and past the valve 80 to the discharge conduit 12, the pressure of the fluid holding the valve 82 closed.

The pump apparatus is designed for eflicient operation and for ready accessibility of working parts, enabling the apparatus to be easily keptin good working condition. The customary type of pump operatedA by a swash plate mechanism is of a design requiring rotation of the pump unit. That entails valving complication. It also necessitates a close inter-relation of the power transmission mechanism and the pump, rendering working parts difllcult of access and also permitthe transmission mechanism. For the latter reason it is necessary to employ oil as the pumping fluid in such a pump. My improved pump apparatus avoids said objectionable features. The improved design of the power transmission mechanism enables a cooperating fixed pump unit to be employed, with consequent simplification of the valving. It enables the pump unit to be mounted in a desirable' spaced relation to the power transmission mechanism, thereby preventing leakage from the pump cylinders to said mechanism and enabling water to be employed as the pumping fluid, if desired. All of the working parts of the pump are rendered readily accessible and removable so that they may be kept in good working condition. 'I'he plugs 8| and 8,3. over thedischarge andintake valves of the pump, have heads freely exposed in straight rows and in stepped relation, to facilitate 'engagement by a wrench, to unscrew the plugs and to get at the valves.

Another desirable feature is the removability of the pump unit en bloc from the power transmission unit without disturbing any parts of the latter. lThe pump unit may be readily detached by unscrewing the nuts 91 at the front face of the pump and unscrewing the plungers from the crossheads 33. The crossheads then remain part of the transmission assembly and the mutual fit of the crossheads and their guides 32 prevents escape of lubricating oil from the casing I and also prevents entrance of water into the casing. Different pump units, possibly of different capacity, may be interchangeably connected to a single transmission unit.

What I claim is: Y

1. A pump unit comprising a plurality of pump cylinders and plungers arranged in a series around a circle and disposed in parallel relation, straight-parallel outlet and inlet conduits disposed transversely of the longitude of the pump cylinders and plungers, fluid communications between the pumpl cylinders and said conduits at points spaced along the latter, a row of valves alongeach conduit to open and close said communications, the conduits having apertures spaced therealong for'insertion and removal of said valves, and removable plugs closing said apertures. l

2. A pump unit comprising an integral block with a plurality of parallel bores for pump `cylinders arranged in a circular series, and with a pair of straight parallel bores extending crosswise of said series and spaced fromone end of the bores in the series, said pair of bores forming outlet and inlet conduits and the block having bores forming uid communications between the bores `of the circular series and said conduits at spaced points/along the latter, a row'ofcheckvalves along each of said conduits to control said communications, the block having afpair of external surfaces in stepped relation for the purpose set forth extending along said conduits and rows of threaded bores opening from the conduits through said surfaces for insertion and removal of said valves, and screw plugs closing said threaded bores.

'3. A pump unit comprising a block with a plurality of parallel bores forpump cylinders arranged in a 4circular series, and with a pair of straight parallel bores extending crosswlse of said seies/and spaced from one end of the bores in thesferies, said pair of bores forming outlet and inlet conduits and the block having bores forming fluid communications between the bores of the circular series and the said conduits at spaced points along the latter, a row of check valves along each of said conduits to control said communications, the block having rows of bores opening transversely from the conduits to the exterior of the block for insertion and `removal of said valves, and removable -closures for said latter bores.

t 4.'A pump apparatus including in combinaing by the driving memberf apump unit exposed at the exterior of said casing and mounted in a position spaced from an outer wall of the casing and having pump cylinders, plungers in saidl cylinders, packings for said plungers, and valves to control ow'through the pump unit and including a series of inlet valves and a series of `outlet valves, thev pump unit having al straight horizontal row of apertures opening upward through an outer wall of the pump unit at one level and through which the inlet valves are in sertlble and removable and a parallel row of apertures opening upward through an outer wall of the pump unit at another level and through which the' outlet valves are insertible and removable and said rows being transverse to the pump cylinders and at the end thereof remote from the transmission unit, the cylinders opening into the space between the pump unit and said casing wall and the wall having apertures opening into said space; and operative connections betweensaid follower member and the pump plungers extending through said casing wall apertures, the latter apertures being sealed against passage of iluid therethrough past said operative connections.

5. A pump apparatus comprising a casing adapted 'to -contain an oil bath, a drive shaft4 extending through said casing, a swash member Within thecaslng and tiltably mounted on said shaft, a follower member within the casing and mounted 0n the swash ,member for universal swash rocking thereby and held against rotation therewith about the shaft axis, said swash member being of elongated tubular form, encircling the shaft and being pivotally connected to the shaft for tilting on an axis transverse to the shaft, a swash adjusting member disposed within the casing and mounted on the lshaft to shift therealong, 'a pulland-thrust linkage connection pivoted at one end to said adjusting member and pivoted at its opposite end to the swash member at a po t spaced materially along the swash member fr, the pivotal connection of the latter with the sha'ft and arranged in an angular relation to theshaft to constitute with the swash member a toggle mechanism to tiltably adjust @the swash member by shift of said adjusti4 d 5 ing operatively connectedat points around the shaft axis to said crossheads, and operative connections between the outer ends of the crossheads and the pump plungers releasable from the exterior of said wall, the space between the wall and the pump body being laterally accessible` for release of said operative connections and for servicing the plunger packings.

6. A pump driving apparatus comprising a casing adapted to contain an oil bath, a drive shaft extending through said casing, a swash member Within the casing and tiltably mounted on said shaft, a follower member within the'casing and mounted on the swash member for' universal swash rocking thereb and held against rota-v tion therewith about t e shaft axis, s'aid swash member being of velongated tubular form, encircling the shaft, and being pivotally connected to the sliaft for tilting on an axis transverse to the shaft, avswash adjusting member disposed within the casing and mounted on the shaft to shift therealong, a pull-and-thrustlinkage connection pivoted at one. end to said adjusting member and pivoted at its opposite end to the swash member at a point spaced materially along `.the swash member from the pivotal connection swash member on the shaft, the follower member being annular and havingantifrictiodn bearings between it and the swashl member to resist radial and axial thrust, a wall of the casing opposed to a face of the follower member having apertures, and crossheads slidably mounted in said apertures and having their outer ends exposed to the exterior of the casing and releasably connectible at the exterior of the casing to pump plungers, said follower member being operatively connected at points around the shaft axis to said crossheads. A

7. A pump apparatus comprising a casing adapted to contain an oil bath, a drive shaft 'ex tending through said casing, .a tubular swash',

member pivotally mounted on and encircling the shaft within the casing to tilt"on an axis transverse to the shaft, an annular follower member within the casing and encircling the swash mem* ber transversely of the said shaft and formed with a. tubular portionsurrounding the-.swash member, anti-friction bearings between the tubular portion of the follower member and the swash member to resist radial thrust and axial thrust vin either direction, the follower member' being arranged close to an end wall of the casing and the tubular portion thereof extending away from the said end wall, means holding the Afollower member against rotation about the said shaft, a circular series of sliding crossheadsl mounted in said end wall of the casing their outer ends being exposed outside of the casing, a connecting rod between the inner end of eachof said crossheads and the follower member, a pump adjacent said end wall of the casing and including pump plungers operatively connected to the ex-..

connection 'pivoted at one end to said adjusting member .and pivoted'at its opposltefend to the swash member at a point spaced materially along the swash member from the pivotal connection of the latter with the shaft and arranged in an angular relation to the shaft to constitute with the swash member a toggle mechanism to tiltably adjust the swash member by shift of said adjusting member and with increasing mechanical advantage as the tilt is increased by shifting of the adjusting member toward the pivot of the swash member on the shaft.

8. A pump driving mechanism comprising a drive shaft, a swash member mounted o'n said shaft, a, follower member mounted on the swash member for universal swash rocking thereby, held against rotation therewith about the shaft axis and operatively connectible to pump plungers at points spaced around the shaft axis,y a gimbal ring l surrounding the shaft axis and having inwardly extending trunnions diametrically arranged, said follower member having bearing recesses for. receptiony of said trunnions and open at one side in the direction of the shaft axis forbentry of the,

trunnions', said gimbal ring having opposite outwardiy extending trunnions on a diameter at a right angle to said rst trunnions, bearing members rotatably receiving said outwardlyy extending trunnions, fixed guides supporting said bearing members for shifting of the same along the shaft axis, and springs urging said bearing membe'rs along their said guides to urge the gimbal.

ring along the shaft axis to hold said inwardly extending trunnions pressed into said bearing recesses of the follower member.

FRANK L. DAVIS, JR. 

